Obesity and psychopathology are common in children with hypothalamic/chiasmatic gliomas (HCG) and craniopharyngiomas (CR). The aims of this study include: (1) To treat tumor-related obesity with combined pharmacologic therapy (phentermine with dl-fenfluramine or fluoxetine) and behavior modification; (2) To assess metabolism and body weight; and (3) To establish standard psychiatric diagnoses in this population. Methods used included: Anthroprometric assessment, bone density, body composition, resting and total energy expenditure with doubly labeled water and the diagnostic interview for children and adolescents (DICA), a structured psychiatric interview were completed. From March 1997 to September 1997, the medications used were dl- fenfluramine and phentermine. Five patients were enrolled and treated for greater than three months. All patients were between 165% to 243% of ideal body weight (IBW). Weight loss ranged from 2.9kg-13.2kg (mean = 7.5 kg). There was no significant toxicity and all echocardiograms were normal. All 5 patients fulfilled the criteria for both major depressive disorder or mood disorder, depressed type and post traumatic stress disorder. Four patients had secondary ADHD and 3 had generalized anxiety disorder. Only 1 patient had either pre-morbid obesity and pre-morbid psychiatric diagnosis. The FDA removed dl-fenfluramine from the market and this protocol was changed to the use of prozac and phentermine in November of 1997. Three new patients have been enrolled and treated for three months. These patients are between 160% and 255% of IBW. Thus far, weight loss has ranged from 4.1kg - 5.9kg (mean = 5kg). There has been no significant toxicity and all echocardiograms are normal. The study is expected to have 26 participants. Currently, active recruitment is underway. To date, conclusions include: (1) Weight loss is possible in children with morbid obesity due to hypothalamic/chiasmatic gliomas and craniopharyngiomas with combined pharmacologic and behavioral management. (2) The incidence of multiple psychiatric diagnoses is high and warrants further investigation and appropriate treatment strategies.